In the scenario of adaptive streaming, a common video sequence often is coded to multiple streams at different bit rates. Each stream is often partitioned to a sequence of transmission units (called “chunks”) for delivery. A manifest file often is created that identifies the bit rates available for the video sequence. In a streaming service, for example, video streams and accompanied playlist files are hosted in a server. A player in a client device that gets stream information by accessing the playlist files and switches among different streams according to estimates of available bandwidth. However, current coding systems do not efficiently accommodate switches among different coding streams representing a common video content item.
Chunk partitions typically are set to include a predetermined amount of coded video data. For example, chunks may be defined to include five seconds of coded video data each. When a player switches from a first stream to a second stream, both streams representing a common video content item coded at different coding rates, the player may retrieve chunks of coded video data of the new stream and attempt to decode them. Decoding may not be possible, however, if the coded chunks of the new stream rely on other chunks as prediction references. In this circumstance, a player may have to skip decoding of portions of the new stream that rely on predecessor chunks as prediction references which may interrupt continuity of video playback. Alternatively, the player may have to request and decode the predecessor chunks in order to generate a continuous video sequence for playback. In the latter case, the predecessor chunks of the new stream likely include coded video data that is redundant to some portion of the chunks that were received and decoded from the old steam. In either case, switching among the streams causes performance impairments at the video decoder and player.
Accordingly, the inventors have identified a need in the art for video streaming techniques that provide efficient switching among different coded streams of a common video sequence.